The present invention relates to a lithium secondary battery (hereinafter simply referred to as “battery”) and an assembled structure of lithium secondary batteries coupling structure (hereinafter simply referred to as “coupling structure”), and more particularly, to a lithium secondary battery with an excellent space-saving characteristic and an assembled structure of lithium secondary batteries with an excellent space-saving characteristic and excellent productivity.
Lithium secondary batteries are widely used as power supplies for portable communication devices and electronic devices such as notebook personal computers in recent years. Furthermore, with a growing international demand for saving of resources and saving of energy for global environmental protection, the development of lithium secondary batteries as motor drive batteries for electric-powered vehicles and hybrid electric-powered vehicles (hereinafter simply referred to as “electric-powered vehicle, etc.”) is underway.
As shown in FIG. 9 and FIG. 10, this lithium secondary battery is generally constructed of an inner electrode body 1 made up of a positive electrode plate 2 and a negative electrode plate 3 arranged in such a way to wind around the periphery of a hollow cylindrical core 16 through the medium of a separator 4 and impregnated therein with a non-aqueous electrolyte, a cylindrical battery case 11 with both ends left open and being used for housing the inner electrode body 1 (sometimes hereinafter referred to as battery case), and two caps 13 for sealing the inner electrode body 1 at both open ends of the battery case 11.
Of the components described above, the caps need to be provided with a current leading function to lead a current generated in the inner electrode body outward, a depressurizing function to prevent bursting of the battery when a pressure inside the battery increases abnormally, and a function as an electrolyte inlet to inject an electrolyte into the inner electrode body housed in the battery case 11.
According to the battery in FIG. 9, the current leading function of this cap is often constructed by attaching a current collector tab 5A for the positive electrode and a current collector tab 5B for the negative electrode (hereinafter also referred to as “tabs 5A and 5B”) to the positive electrode plate 2 and negative electrode plate 3 (hereinafter also referred to as “electrode plates 2 and 3) of the aforementioned inner electrode body 1 respectively, attaching the opposite ends of the tabs 5A and 5B connected to the electrode plates 2 and 3 to a positive internal terminal 14A and negative internal terminal 14B (hereinafter referred to as “internal terminals 14A and 14B”) which are the members for temporarily collecting a current inside the cell and placing a positive external terminal 15A and a negative external terminal 15B (hereinafter also referred to as “external terminals 15A and 15B”) which are the members electrically connected with the internal terminals 14A and 14B for leading the current out of the battery.
At this time, the positive and negative external terminals 15A and 15B are provided on both ends of the battery case 11. However, since external terminals need to have a protruding structure from the battery outward for functional reasons, there is a problem that a size of the battery grows accordingly, which requires a larger space for housing the battery in an intended place or portion.
On the other hand, when a lithium secondary battery is used for motor driving of an electric-powered vehicle, etc., many batteries are connected in series to secure a voltage necessary for driving the motor. Thus, depending on the assembled structure of lithium secondary batteries, a large space is required, which then causes a problem of reducing a volume energy density of the assembled structure of lithium secondary batteries.